The present invention is directed to a microwave dual mode non-interfering CW and pulsed signal system principally desirable for electronic countermeasures equipment.
Modern ECM equipment can be grouped into the categories of CW, pulsed, and dual mode signal systems. CW systems have the capability of providing continuous wave transmission and generally employ some type of noise modulation to degrade enemy radars. Pulsed systems respond to the threat radar on a pulse by pulse basis and function through deceptive techniques. The designation of a "dual mode" system implies the ability for the system to provide CW or pulsed, or a combination CW and pulsed transmission.
Because certain threats are best handled with CW capability and other threats are best countered with pulsed capability, it is desired for versatility to incorporate dual mode capability. This desire has been recognized for many years, and although some existing equipments incorporate dual mode capability, several limitations exist. An optimum dual mode system would have the inherent CW capability of a CW-only system and the pulsed capability of a pulsed-only system. In present dual mode systems, one mode or the other has been severely compromised. For example, for one typical application CW systems have the capability of providing 200+ watts of power and pulsed systems 1 to 2 kW of peak power, whereas the dual mode system has the capability of about 200 watts CW and 500 watts pulsed. While it would be desired in a dual mode system to have CW power comparable to what is available in a CW-only system and a pulsed power capability 10 dB higher, existing dual mode systems have pulsed power only about 3 dB higher than the CW capability.
The majority of the effort to design and develop the ideal dual mode system has been directed toward development of a traveling-wave tube amplifier which has the ability to operate CW, pulsed or both. Due to the nature of the interaction process in the traveling-wave amplifier, it has not been possible to design tubes which operate at widely different power levels efficiently and with stability.
In the systems proposed to date using separate CW and pulsed traveling-wave tube amplifiers, either separate antennas must be used for the separate signals or half the power of each tube is lost in combining the power outputs for dual mode operation with one antenna or two antennas can be used, but with each radiating only one-half of the power capability of the separate CW and pulsed tubes.